Open end wrench

ABSTRACT

The invention relates to an open-end wrench having a clamping jaw which is rigidly connected to a wrench handle in a fixed manner. A spring-loaded, moveable clamping jaw is pivotally mounted on the fixed clamping jaw. A recess, which recoils opposite the plane of the clamping surface, is connected to the clamping surface of the fixed clamping jaw on the gripping side. The moveable clamping jaw has a recess located in the area between the clamping surface of the jaw and the pivot point thereof. In an opened state of the wrench, said recess approximately corresponds to the recess behind the fixed clamping jaw. The wrench can be handled similarly to a fixed open-end wrench, whereby it enables a ratcheting action and has a self-clamping operation.

BACKGROUND OF THE INVENTION

The invention relates to an open-end wrench having a fixed clamping jawthat is rigidly connected to a wrench handle and a spring-loadedmoveable clamping jaw whereby said moveable clamping jaw is pivotablymounted at a pivot point on the fixed clamping jaw and whereby saidpivot point is disposed approximately at a right angle or at an angle ofless than 90° behind the rear end of the clamping surface of themoveable clamping jaw.

One-piece open-end wrenches with two jaws, which are rigidly joined withone another, have the advantage, compared to wrenches having jaws thatmove relatively to one another, that sufficient torque may betransferred since the mouth of the wrench sufficiently embraces theworkpiece, e.g. a bolt head or a nut. The access to the workpiece isergonomically favorable especially since the wrench handle extends fromthe middle of the wrench head. The hand can therefore be moved forwardup to the wrench head to guide the open-end wrench during placement (onthe workpiece) by touch or to conduct a necessary manipulation of theworkpiece, for example, to hold a nut that rotates easily. The open-endwrench may be slipped on or removed without hitting neighboringcomponents.

However, rigid open-end wrenches have several disadvantages. Forinstance, the open-end wrench has to be pulled off and slipped on againafter each turning sequence. If there is only a 30° movement possiblefor one turning sequence, then the open-end wrench has to beadditionally turned around. This causes a considerable additionalexpenditure in time.

The widening of the wrench head caused by strain on the wrench head maylead to hazardous conditions. This applies particularly when thetolerances of the wrench width are added to the tolerances of theworkpiece. Rigid open-end wrenches may be employed only for one nominalwidth and cannot be fitted to the tolerances of the workpiece.Rounded-off corners of the workpiece and misuse of nominal metric orwidths in inches that are close in measurement lead also to the dangerthat the wrench may slip off the workpiece, which in turn leads to anincreased risk of an accident. Even if a metric width or a width ininches is close, there are special rigid open-end wrenches necessarywhereby the assortment of sizes is increased.

Since rigid open-end wrenches are not self-clamping, they can slip moreeasily in the direction of the rotating axis of the workpiece wherebythe risk of an accident is increased as well. There is the lack of thepossibility of adjustment to the dimensions of the workpiece, whereas itis made possible with a self-clamping action. There is also the lack ofthe possibility of adjustment to the operational process; for instance,the open-end wrench may not be left on the workpiece in a self-clampingposition while intermediate operational steps are to be performed, orwhile working overhead.

The here referenced wrenches are to maintain the advantages of theopen-end wrenches, avoid their disadvantages, and provide additionaladvantages. Particularly, it should be possible (but not absolutelynecessary) to select a shape that is similar to a rigid open-end wrench.The wrench should be able to work in a ratcheting action in sequences of30° and should be self-clamping.

Even though there are open-end wrenches known in many differentconfigurations, none of them fulfill all the above-mentionedrequirements.

Open-end wrenches with two moveable clamping jaws (U.S. Pat. No.4,584,913) are of relatively complicated construction and are thereforecostly to manufacture and they malfunction easily. In another version ofan open-end wrench (CH-A 365 348) there occurs mutual locking of the twoclamping jaws by swiveling the handle, which is connected to one of theclamping jaws by a joint. The construction is here also relativelycomplicated and therefore is malfunctions easily; manipulation requiresa lot of space for the swiveling movement of the handle.

The guiding of the moveable clamping jaw on an arch (U.S. Pat. No.5,287,777) causes very high demands in manufacturing and also causesmalfunction through build-up of dirt and wear.

On a known wrench (U.S. Pat. No. 2,907,243), the moveable clamping jawis moved longitudinally against the force of a spring on a guide, whichis rigidly connected to the fixed clamping jaw. The necessarymanufacturing demands are here also relatively high; the construction ofthe wrench causes a certain malfunctioning from build-up of dirt and/orwear. The wrench cannot be simply pulled off, gripping by hand isnecessary near the bolt head to move the mobile jaws. This appliesparticularly also during the placement of the wrench (on the workpiece).Employment is therefore only possible when the wrench head isaccessible.

This known wrench is not self-clamping since the moveable clamping jawrests against a stop surface in its terminal position. The wrench doestherefore not fulfill the requirement mentioned in the beginning.

Wrenches that have toothed clamping jaws (U.S. Pat. No. 4,616,534, DE-A196 12 759) may be ratchet-operated in small increments because of theteeth; the engagement of teeth on the workpiece may, however, lead todamages so that these wrenches cannot be employed in the industrial areaor on sensitive workpieces, for instance in the bolting operation inplumbing.

On a known wrench of the type mentioned in the beginning (U.S. Pat. No.1,735,257), the clamping surface on the moveable clamping jaw, withwhich the clamping force is exerted onto the workpiece, is designed witha flat surface. The opposed clamping surface of the fixed clampingsurface is convex arcuated. With this wrench, the bolting process may beperformed only by ratcheting movements of 60°.

It is therefore the object of the invention to design an open-end wrenchof the type mentioned in the beginning that has essentially the functionof a rigid open-end wrench but which is self-clamping, and which makespossible ratchet movements of 30° whereby the necessary swivelingmovement of the wrench handle does not substantially amount to more than30° itself.

It is therefore the object of the invention to design an open-end wrenchof the type mentioned in the beginning that has essentially the functionof a rigid open-end wrench but which is self-clamping and which makespossible ratchet movements of 30° whereby the necessary swivelingmovement of the wrench handle itself does not substantially amount tomore than 30°.

SUMMARY OF THE INVENTION

This object is achieved according to the invention in that each clampingsurface is subdivided by at least two convex arcuated clamping teeth;that a recess, which recoils opposite the plane of the clamping surface,is connected on the side of the handle to the clamping surface of thefixed jaw, and that the moveable clamping jaw is provided with a recessin the area behind the clamping surface and the pivot point and whichrecess approximately corresponds to the recess behind the fixed clampingjaw in the open position of the wrench.

As a result of its self-clamping function, the wrench adjusts itself tothe dimensions of the workpiece so that especially the deviation derivedfrom the tolerance is compensated and does not lead to the danger ofslipping. The widening of the mouth of the wrench is also compensated bythe self-clamping effect and this does not lead therefore to possibleslipping. Only one single wrench is necessary for nominal widths in themetric and inch-system whereby the amount of the required wrenchassortment is decreased.

The self-clamping effect makes also possible to leave the wrench on theworkpiece in a self-clamping manner if said wrench has to be releasedbecause of a necessary intermediate operational step. The wrench doesalso not fall down when released during work overhead.

The wrench may be ratchet-operated in increments of 30° so that it doesnot have to be pulled off and slipped on anew. The time in handling isthereby decreased considerably.

Only by the provided recess behind the clamping surfaces of the twoclamping jaws has it been made possible to manipulate the self-clampingwrench in a ratcheting movement since only through these recesses enoughspace has been created to move the wrench back over the workpiece onlywith minute widening of the wrench mouth. The swiveling motion of thewrench handle, as performed during ratcheting action of approximately30°, is only a little more than 30°. The wrench can therefore beemployed also under very tight working conditions. Nevertheless, thewrench has substantially the shape and dimensions of a rigid open-endwrench and may be handled just as simple.

According to one embodiment of the invention it is proposed that themoveable clamping jaw protrude with one joint eye into the longitudinalslot that runs from the fixed clamping jaw into the wrench handle.Thereby the parts moving relatively to one another are arranged in a wayto be protected so that there is achieved a smooth and compact design ofthe wrench. The spring, which communicates with the moveable clampingjaw, is preferably a tension spring that is braced against the wrenchhandle and which pushes the moveable clamping jaw in the direction ofits clamping position. This tension spring is preferably a leaf springattached to the wrench handle whereby said spring is mainly arranged inthe longitudinal slot and whereby it does not interfere with thehandling of the wrench and cannot be damaged.

If the center segment of the leaf spring does protrude from thelongitudinal slot in the open position of the wrench, then the moveableclamping jaw can be moved by applying pressure on this center segment.

According to a preferred embodiment of the invention, it is proposedthat the moveable clamping jaw is provided with a stop surface that isangled relative to the clamping surface and which connects to theclamping surface on the handle side. This stop surface prevents that thewrench embraces the workpiece too far when slipped on and after eachratcheting action.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiment examples of the invention are described in more detail below,which are also illustrated in the drawings.

FIG. 1 shows a wrench in a longitudinal view in a first clampingposition.

FIG. 2 shows the wrench according to FIG. 1 in an intermediate positionduring the ratcheting action.

FIG. 3 shows the wrench according to FIG. 1 and FIG. 2 in a secondclamping position being 30° displaced relative to FIG. 1.

FIG. 4 shows a modified embodiment of the wrench similar to a ⅚-ringwrench.

FIG. 5 shows an additional modified embodiment of the wrench.

FIG. 6 shows a relationship between the clamping surface and the pivotpoint of the moveable jaw of the wrench.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

The wrench illustrated in FIG. 1 through FIG. 3, which is similar in itsouter dimension and in handling to an open-end wrench, is provided witha wrench handle 1 that is connected to a fixed clamping jaw 3 via aright-angled transition piece 2. A moveable clamping jaw 4 protrudeswith a joint eye 5 into a longitudinal slot 6, which runs from the fixedclamping jaw 3 into the wrench handle 1. A pivot pin 7 forms the pivotbearing for the moveable clamping jaw 4.

A workpiece 8 that is received in a wrench, for example a hexagon bolthead, lies in the horizontal clamping plane 9 of the fixed clamping jaw3 and the horizontal clamping plane 10 of the moveable clamping jaw 4.The pivot point 11 of the pivotable clamping jaw 4, which is determinedby the pin 7 and which can be seen in FIG. 1, lies approximately in aright angle at the rear end 10 a of the clamping surface 10 of themoveable clamping jaw 4. The angle may also be smaller. Stated anotherway, the peaks of the front and rear teeth 10 b lie on a reference lineR which terminates at a termination point disposed at a peak of the reartooth 10 b; an imaginary line L extending from that termination point tothe pivot point 11 forms an angle α not greater than about ninetydegrees with the reference line, as shown in FIG. 6.

Both clamping surfaces 9 and 10 are formed by two convex arcuatedclamping teeth 9 b or 10 b, which are separated from one another by anotch 9 d or 10 d. The flanks of the notches 9 d and 10 d of theclamping surface 9 or 10 are disposed in an angle of less than 120° toone another. This leads to the fact that in the second clamping positionshown in FIG. 3, the corners are not gripped but the neighboring,connecting surface segments of the workpiece 8 are gripped by theclamping surfaces 9 and 10. The pressure on the corners of the workpieceis thereby removed and the danger of slipping is avoided.

A leaf spring 12 is attached to the wrench handle 1 with its one end 12a and extends into the longitudinal slot 6. The other rounded-off, freeend 12 b of the leaf spring 12 rests against the rear side 4 a of themoveable clamping jaw 4 and pushes it into its clamping position. On therear side 4 a of the moveable clamping jaw 4 there may be provided alocking recess 13 into which the free end 12 b of the leaf spring 12comes to rest to keep the moveable clamping jaw 4 in its open positionfor removal.

On the clamping surface 9 of the fixed clamping jaw 3 there is a recess14 that is connected at its rear end 9 a on the handle side whereby saidrecess 14 recoils relative to the plane of the clamping surface 9. Themoveable clamping jaw 4 is also provided with a recess 15 in the areabetween the clamping surface 10 and the pivot point 11, whichapproximately corresponds to the recess 14 behind the fixed clamping jaw3 in the open position of the wrench (FIG. 2).

These two recesses 14 and 15 provide a space for the workpiece 8 duringthe ratcheting action (FIG. 2) whereby the moveable clamping jaw 4 doesnot have to be opened too far. This makes possible to spread out thepart of the moveable clamping jaw 4 that extends over the entire wrenchwidth in a relatively widespread fashion in the direction toward thepivot point 11. Thereby the right-angled segment 2 does not interferewith the movement of the moveable clamping jaw 4. The moveable clampingjaw 4 is therefore provided with a stop surface 16 on the handle sidethat is angled relative to the clamping surface 10 and which isconnected to said clamping surface 10 whereby said stop surface servesas a guide for the wrench on the workpiece 8 as can be clearly seen inFIG. 3, for example.

During the ratcheting action, the wrench is pivoted relative to theworkpiece until the corners of the workpiece 8 enter the notches 9 d or10 d (FIG. 2 shows an intermediate position during pivoting). In thesecond clamping position, as illustrated in FIG. 3, the workpiece 8 isrotated anew with the wrench by an additional rotating sequence of 30°,for example.

While in the embodiment examples in FIG. 1 through FIG. 3 the wrenchhandle 1 extends substantially in the opposite direction of the mouthopening of the wrench, the handle in the embodiment example in FIG. 4forms an angle of approximately 30° relative to the mouth opening. Thepivot point 11 for the pivoting movement of the moveable clamping jaw 4is hereby displaced near the longitudinal axis of the handle 1, whereasit is displaced laterally relative to this longitudinal axis in theexample in FIG. 1 through FIG. 3. The wrench in FIG. 4 has therebyapproximately the outer shape of a so-called ⅚-ring wrench. The clampingsurface 9′ or 10′ of the fixed clamping jaw 3 or of the moveableclamping jaw 4 are hereby formed by a plurality of convex roundedclamping teeth, which are disposed on an arch.

The moveable clamping jaw 4 is hereby connected to an actuatingprotrusion 17, which extends toward the wrench handle 1, and which makespossible to open the wrench against the force of the leaf spring 12.

Such wrenches are especially advantageous for the use on hydrauliclines, e.g. brake lines, or for threaded rods. Self-clamping action ishere of particular importance—especially to avoid slipping sidewise.

As shown in FIG. 4 by dashes, the center segment 12 c of the leaf spring12 bows outside the longitudinal slot 6 in the open position of thewrench (the moveable clamping jaw 4 is illustrated by dots and dashes).After locking of the free end 12 b of the leaf spring 12 in the lockingrecess 13, the moveable clamping jaw can be again pivoted into itsoperational position whereby one pushed with his thumb on the arcuatedcenter segment 12 c. This configuration of the wrench in FIG. 4 isespecially favorable under ergonomic view points since the hand grippingthe wrench handle 1 can actuate with its index finger the protrusion 17and can actuate with its thumb the center segment 12 c of the leafspring 12.

In FIG. 4 there is indicated by an arch 18 in dashes that thelongitudinal slot 6 may be produced in a single, simple cutting processby using a disk milling cutter.

The embodiment example in FIG. 5 differs from the example in FIG. 1through FIG. 3 substantially in that the moveable clamping jaw 4 isprovided with two joint cheeks 20, which are separated from one anotherby a slot 19, whereby said joint cheeks embrace the right-angled segment2 on both sides and receive it in between. A leg spring 21 is arrangedbetween the two joint cheeks 20 and it is braced against the wrenchhandle 1 on one side and on the rear side of the moveable clamping jaw 4on the other side. The leg spring 21 is thereby completely coveredwithin the wrench head. The slot to be cut out between the two jointcheeks 20 is easier to be manufactured than the longitudinal slot 6 ofthe previously described embodiment examples. The workpiece is embracedwith all surfaces in this embodiment. A stop surface 3 a of the fixedclamping jaw 3 on the handle side limits the possible rotating movementof the moveable clamping jaw 4 and determines thereby the fully closedposition of the wrench.

All illustrated embodiments have in common that the fixed clamping jaw 3is not cut out in the center but it makes contact against the workpiece8 with its entire surface. The version of the clamping surfaces 9 and9′, 10 and 10′ with their convex arcuated clamping teeth contributeadditionally that during the ratcheting action less friction is exertedon the workpiece 8. This may be of significance especially in the use onsensitive workpieces, for instance during plumbing installation.

What is claimed is:
 1. An open-ended wrench comprising: a wrench handle;a fixed clamping jaw rigidly connected to the handle; and aspring-loaded movable clamping jaw pivotably mounted to the fixed jaw ata pivot point; the fixed jaw including a fixed clamping surface, and themovable clamping jaw including a movable clamping surface disposedgenerally opposite the fixed clamping surface, the fixed and movableclamping surfaces together forming a cavity for receiving a workpiece;the fixed clamping surface including a plurality of convexly curvedfixed clamping teeth, wherein adjacently disposed ones of the fixedteeth are separated by a notch, the plurality of fixed teeth including apair of front and rear convexly curved fixed clamping teeth disposedadjacent a mouth of the cavity and oriented such that peaks of the frontand rear fixed teeth together define a fixed clamping surface, the frontfixed clamping tooth being disposed closer to the mouth than is the rearfixed clamping tooth; the movable clamping surface including a pluralityof convexly curved movable clamping teeth, wherein adjacently disposedones of the movable teeth are separated by a notch, the plurality ofmovable teeth including a pair of convexly curved front and rear movableclamping teeth disposed adjacent the mouth of the cavity and orientedsuch that peaks of the front and rear movable teeth lie on a referenceline which terminates at a termination point disposed at a peak of therear movable tooth, an imaginary line extending from that terminationpoint to the pivot point forms an angle not greater than about ninetydegrees with the movable clamping surface; the movable jaw including aconcavely curved recess extending from a rear end of the rearwardmostone of the plurality of movable teeth to a location adjacent the pivotpoint.
 2. A wrench according to claim 1, wherein the movable jaw isdisposed within a longitudinal slot formed in the fixed jaw and thewrench handle.
 3. A wrench according to claim 2, wherein a spring whichis braced against the wrench handle, pushes the movable jaw toward aclamping position.
 4. A wrench according to claim 3, wherein the springcomprises a leaf spring attached to the wrench handle and arrangedmainly in the longitudinal slot.
 5. A wrench according to claim 4,wherein a center segment of the leaf spring bows out from thelongitudinal slot in an open position of the wrench.
 6. A wrenchaccording to claim 1, wherein the movable jaw is provided with a stopsurface on the handle side that is angled relative to the movableclamping surface and which is connected to the movable clamping surface.7. A wrench according to claim 1, wherein each notch includes flanksdisposed at an angle of less than 120 degrees to one another.
 8. Awrench according to claim 1, wherein the movable jaw comprises two jointcheeks separated by a slot.
 9. A wrench according to claim 8, wherein aleg spring is arranged between the joint cheeks and is braced againstthe movable jaw.
 10. A wrench according to claim 1, wherein the movablejaw includes a stop surface engageable with the fixed jaw for defining afully closed position of the movable jaw.